"Everything indicates that this was an accident resulting from several unfortunate circumstances that allowed the woman to set the train in motion in connection with the cleaning," prosecutor Pär Andersson told the press.

Immediately following the accident, both Stockholm's public transit company SL and the line's operator Arriva said they believed they cleaner had stolen the train, but now claim they made no absolute statements.

"I made clear from the beginning that all scenarios were possible. It's unfortunate that she was depicted as a thief, and I'm truly sad about that," said Arriva spokesman Tomas Hedenius.

The woman herself has not yet been interviewed by police as she remains in serious condition.

Andersson, the prosecutor, said his office is currently investigating possible workplace safety violations.